<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        var str1 = 'Hello JS and Java';
        console.log(str1.indexOf('J'));//6
        console.log(str1.indexOf('JS'));//6
        console.log(str1.indexOf('JS', 9));//-1
        var str2 = 'how are you doing today';
        var array = str2.split(' ');
        console.log(array);
        console.log(array[0]);
        // "".isEmpty()
        console.log('1:2:3:4'.split(':'));
    </script>
</head>
<body>

</body>
</html>